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From: Felix Fietkau <nbd@nbd.name>
Subject: kernel: add a config option for keeping the kallsyms table uncompressed, saving ~9kb kernel size after lzma on ar71xx
[john@phrozen.org: added to my upstream queue 30.12.2016]
lede-commit: e0e3509b5ce2ccf93d4d67ea907613f5f7ec2eed
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
init/Kconfig | 11 +++++++++++
kernel/kallsyms.c | 8 ++++++++
scripts/kallsyms.c | 12 ++++++++++++
scripts/link-vmlinux.sh | 4 ++++
4 files changed, 35 insertions(+)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1482,6 +1482,17 @@ config SYSCTL_ARCH_UNALIGN_ALLOW
the unaligned access emulation.
see arch/parisc/kernel/unaligned.c for reference
+config KALLSYMS_UNCOMPRESSED
+ bool "Keep kallsyms uncompressed"
+ depends on KALLSYMS
+ help
+ Normally kallsyms contains compressed symbols (using a token table),
+ reducing the uncompressed kernel image size. Keeping the symbol table
+ uncompressed significantly improves the size of this part in compressed
+ kernel images.
+
+ Say N unless you need compressed kernel images to be small.
+
config HAVE_PCSPKR_PLATFORM
bool
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -69,6 +69,11 @@ static unsigned int kallsyms_expand_symb
* For every byte on the compressed symbol data, copy the table
* entry for that byte.
*/
+#ifdef CONFIG_KALLSYMS_UNCOMPRESSED
+ memcpy(result, data + 1, len - 1);
+ result += len - 1;
+ len = 0;
+#endif
while (len) {
tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
data++;
@@ -101,6 +106,9 @@ tail:
*/
static char kallsyms_get_symbol_type(unsigned int off)
{
+#ifdef CONFIG_KALLSYMS_UNCOMPRESSED
+ return kallsyms_names[off + 1];
+#endif
/*
* Get just the first code, look it up in the token table,
* and return the first char from this token.
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -77,6 +77,7 @@ static struct addr_range percpu_range =
static struct sym_entry **table;
static unsigned int table_size, table_cnt;
static int all_symbols;
+static int uncompressed;
static int absolute_percpu;
static int base_relative;
static int lto_clang;
@@ -605,6 +606,9 @@ static void write_src(void)
printf("\t.long\t%u\n", table[i]->seq);
printf("\n");
+ if (uncompressed)
+ return;
+
output_label("kallsyms_token_table");
off = 0;
for (i = 0; i < 256; i++) {
@@ -656,6 +660,9 @@ static unsigned char *find_token(unsigne
{
int i;
+ if (uncompressed)
+ return NULL;
+
for (i = 0; i < len - 1; i++) {
if (str[i] == token[0] && str[i+1] == token[1])
return &str[i];
@@ -728,6 +735,9 @@ static void optimize_result(void)
{
int i, best;
+ if (uncompressed)
+ return;
+
/* using the '\0' symbol last allows compress_symbols to use standard
* fast string functions */
for (i = 255; i >= 0; i--) {
@@ -889,6 +899,7 @@ int main(int argc, char **argv)
{"absolute-percpu", no_argument, &absolute_percpu, 1},
{"base-relative", no_argument, &base_relative, 1},
{"lto-clang", no_argument, <o_clang, 1},
+ {"uncompressed", no_argument, &uncompressed, 1},
{},
};
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -160,6 +160,10 @@ kallsyms()
kallsymopt="${kallsymopt} --lto-clang"
fi
+ if is_enabled CONFIG_KALLSYMS_UNCOMPRESSED; then
+ kallsymopt="${kallsymopt} --uncompressed"
+ fi
+
info KSYMS ${2}
scripts/kallsyms ${kallsymopt} ${1} > ${2}
}
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